As the concern for non-renewable resources has grown over the last decade, so has the awareness of the efficiency of various combustion devices, including domestic furnaces and hot water heaters. With this awareness of combustion efficiency has come the development of various high efficiency home heating devices. These devices operate such that the necessity for a chimney is now removed. However, in the case where a homeowner wishes to upgrade the heating system with a high efficiency furnace, a chimney must be maintained for the use of the conventional gas hot water heater. In other cases, a homeowner has an existing electric hot water heater but requires a faster recovery time as well as the benefit of high efficiency and no need to install a chimney. In both of these cases, the need can be seen to develop a domestic hot water retrofit device that will supply an increased recovery rate at a high efficiency and still utilize the existing tank.